On 2013-03-23 23:48:19 +0000, Charlie said:
On 3/23/2013 7:01 PM, Sheldon Simms wrote:On 2013-03-23 20:53:33 +0000, Charlie said:The problem with any card that uses data from the slot bus is the inability to synchronize with the Apple video output. This is the way the Carte Blanche works and I'm pretty sure the Second-Sight card worked in a similar way (although I've never seen one). The Carte Blanche output visually is quite good although it doesn't have the NTSC look. This works well with most video but because of the lack of synchronization, programs that rely on timing with Vertical Blanking or interrupting to change palettes, modes, etc. don't do well. By the way sampling the bus doesn't have to be that fast. The Carte Blanche does it a 50MHz.50 Mhz is plenty fast enough, I was just wondering whether the Beaglebone can do it that fast.I agree, you probably only need to sample it faster than the Apple writes it which, of course, is much slower.Video sync is a solvable problem. Either take the signal where it is available (IIe slot 7, etc.)That would probably work with a //e but unfortunately not with a IIgs because the M2B0 signal is needed for the SHR graphics modes and M2B0 is not available on slot 7 (and the pin used for it in the other slots is used by CREF). I may try my hand at soldering a wire to connect the Sync signal to the Carte Blanche slot just to see how it works. I can't picture many people wanting to do this though.or write a program that will allow the VGA card/software to sync.Do you mean a program on the Apple II? I don't see how you could do that without interfering with other programs.
Yes, an Apple II program you would run to allow the BeagleBone/VGA Card to sync. Once it's synced it can stay synced as long as it's powered. So you would run the sync program once and then you could do whatever you wanted while remaining synced until you powered down.